1. Field of the Invention
The invention relates to seats for use in vehicles and the like and more particularly to a cushioned seat having improved apparatus and method for retaining the cushion of such a seat on the underlying shell.
2. Description of the Related Art
Cushioned seats for use in vehicles and the like are well known. The typical such seat includes a shell on which is retained an upholstered cushion. Many consumers desire a "unitary" seat appearance in which the apparatus via which the cushion is connected to the underlying shell is not readily visible. Such a construction is not only aesthetically pleasing but also tends to be relatively durable.
A seat of this type is proposed in U.S. Pat. No. 4,836,609 to Hill (the Hill patent). The seat disclosed in the Hill patent includes a shell having a seat portion and a backrest portion and a cushion having complimentary seat and backrest portions. The cushion is retained on the shell by a separate rigid inner support ring having a peripheral edge matching a contoured edge of the shell. The seat and backrest portions of the cushion each have an outer margin secured to an interior surface of the support ring. An outer surface of the inner ring is in turn secured to the inner surface of the shell. This type of seat is commonly known as a "split shell" seat or a seat having a ring or shell within a shell.
While seats of the type disclosed in the Hill patent perform more than satisfactorily, they suffer from certain drawbacks and disadvantages. Most notably, manufacturing and assembling such a seat is a relatively complex and time consuming venture requiring considerable skilled labor and the use of several components which are themselves relatively complex and expensive to manufacture. Manufacture is complicated by the fact that the shell must be formed with forwardly protruding lances and a contoured edge terminating in a flange. Manufacture is also complicated by the fact that the inner ring must formed with rearwardly protruding tabs. During assembly, the cushion must first be aligned with and then attached to the inner ring, and the tabs on the inner ring must engage the lances on the shell so that the lances index and locate the cushion/inner ring subassembly in proper alignment with the seat pan. Releasible fasteners in the form of cap screws or the like must then be inserted to connect the inner ring to mounting recesses formed in the shell. This of course significantly complicates assembly. Assembly is further complicated by the requirement for a finish strip around the terminal flange on the contoured edge of the shell.
Other seats are known which lack the split shell or shell within a shell construction of the type disclosed in the Hill patent. Most of these seats require the direct connection of the cushion or the upholstery layer to the shell using screws, staples, or crimp edging. Such retention devices necessarily impose substantial compression or tension forces that distort the upholstery layer and/or cushion member, thereby detracting from the unitary appearance desired by many consumers and complicating assembly.